Specific Heat of Pure Zinc and Dilute Zinc-Manganese Alloys below 5°K

The specific heats of degassed pure zinc and ZnMn alloys containing 0.02- and 0.05-at.% Mn have been measured in the range 0.4-3^∘{}K, and an alloy containing 0.2-at.% Mn in the range 0.4-5^∘{}K. A new "stud" technique was used to establish thermal contact with the copper-tray calorimeter. For normal pure zinc (0.9-3.0^∘{}K), the electronic specific-heat coefficient is 151.9±{}1.1 {μ}cal/^∘{}K² g-at.---lower than the currently accepted value---and the low-temperature limiting Debye temperature is (329.2±{}3.4)^∘{}K. The temperature of the maximum of the specific-heat anomaly in ZnMn alloys is found to be directly proportional to the concentration in the range 0.02-0.1 at.%. There is therefore no evidence for a change at low concentrations to a concentration-independent temperature of the maximum, as found in CuFe and supposedly characteristic of a Kondo condensation; but experiments to lower concentrations and temperatures would be necessary to confirm this, because present estimates of the Kondo temperature vary from 0.2 to 4.0^∘{}K.